One embodiment relates to an antenna for circular polarization, having an electrical dipole radiator that runs at a distance from the front side of an electrically conductive base surface and in a plane of symmetry oriented perpendicular to the base surface. The antenna has polarization oriented essentially parallel to the base surface, and a feed line that runs in the plane of symmetry toward the base surface.
One way to configure an antenna for circular polarization could include using two different dipole antennas that are structured in the same manner. At least one of the dipole antennas would be oriented perpendicular both to the plane of symmetry of the first dipole antenna and to an electrically conductive base surface. The two dipole radiators are switched together by way of a 90° phase rotation element, and the combined signal is passed to the base surface by way of a feed line. Antennas of this type are known, for example, from DE 4008505 A1. They are frequently used for reception of satellite radio services—such as Inmarsat, SDARS, Worldspace, etc., for example. Particularly when using such antennas on the outer skin of vehicles, it proves to be disadvantageous that the antenna—when the antenna is installed on the outer skin of the vehicle—represents a three-dimensional structure on its outside. Frequently, there is a need, for example when affixing the antenna to a vehicle roof or to a fender, for a two-dimensional structure, or for a substantially two dimensional structure which comprises a flat planar device or fin.
A substantially two dimensional structure to a great extent, has an expanse of which, is minimally transverse to the direction of travel. This is desirable both for reasons of low noise due to air eddies and for stylistic reasons. This requirement applies, to a particular degree, for the parts of the antenna that project beyond the outer skin of the vehicle, while low transverse dimensions in the plane of the outer skin are not problematical. A design such as this then cuts down on noise generated from wind interference.